After a brief overview of most important general features of the nonclassical diffusion on the base of the extended irreversible thermodynamics, the relevant mathematical formulae are incorporated into general formalism of the simultaneous convection-diffusion processes taking place in porous media. Then, using the simplest variant of the convection-diffusion equation, novel-type analytic solutions are derived for transport processes with both subdiffusion and superdiffusion characters in Lagrangian representation.

Digested wastewater sludges have high content of thermophilic fungi because of the anaerobe biodegradation. This study shows the ecophysiological properties (cellulose, hemi-cellulose, lignin and fatty-acid ester degradations) of thermophilic fungi which were isolated from digested wastewater sludge samples. The samples came from three Hungarian wastewater treatment systems. In this study four types of mycological agars were applied. This study shows digestion properties and growing temperature range of eight thermophilic fungal species. This study demonstrated wide ranges of digestion properties. Most of the isolated species are appropriate for degradations of several biopolymers.

The surface carbon dioxide (CO2) fluxes together with the soil microbial biomass and activity in undisturbed soil columns were studied in three growing seasons. Soil columns had six treatments: (1) control without plants; (2) mineral fertilized without plants; (3) no fertilizer and maize plants; (4) mineral fertilized and maize plants; (5) manure and maize plants; (6) mineral fertilized plus manure and maize plants. Soil microbial biomass was measured by substrate-induced respiration (SIR) and microbial activity as fluorescein-diacetate hydrolysing activity (FDA). Treatments had a significant effect (P < 0.001) on CO2 fluxes, SIR and FDA. The presence of maize increased CO2 efflux, SIR and FDA compared to unplanted column. Fertilizer + manure treatment resulted in the greatest plant biomass and the greatest CO2 efflux. Significant correlation (r = 0.680; r = 0.586 in two consecutive years) between SIR and FDA was found.

The heavy meta l adsorption on the surface of fungi compost is one of the alternative technologies. In this study fungi composts were used and we measured the heavy metal adsorption capacities. The laboratorical methods were the preparing solutions of heavy metals, the a dsorptions of heavy metals on the surface of fungi compost by shaking method, the sample degradation and the analytical measurements by ICP - MS. The heavy metal adsorption properties of fungi compost could be used in wastewater treatment because wastewater sometimes contains a high concentration of heavy metals.

A novel-type symmetry analysis of the basic mathematical formalism of some fundamental features of the convection-diffusion and turbulent flows is given on the base of the Riccati-type ordinary and matrix differential equation. Common symmetry features of the turbulent flow velocity and incommensurately modulated crystals are also briefly discussed.

A general description of the basic system of ordinary differential equations of coupled transport processes is given within framework of a linear approximation and treated by tools of matrix analysis and group representation theory. It is shown that the technique of hyperdyads directly generalizes the method of simple dyadic decomposition of operators used earlier in the classical linear irreversible thermodynamics and leads to possible new applications of the concept of quasi-polynomials at descriptions of coupled transport processes.

The basic partial differential equations relevant for convection-diffusion and convection-diffusion-wave phenomena are presented and solved analytically by using the MAPLE symbolic computer algebra system.The possible general nonlinear character of the constitutive equation of the convection-discussion process is replaced by a direct posteriori stochastic refinement of its solution represented for Dirichlet-type boundary conditions.A thermodynamic analysis is performed for connecting the relaxation time constants and Jacobi-determinants of deformations at transient transport processes.Finally,a new procedure for general description of coupled transport processes on the basis of the formalism originally developed for convection-free phenomena is presented by matrix analysis methods in the Fourier space.

There is an increasing interest of the soil gas-phase dynamics due to the elevated greenhouse gas emissions into the atmosphere. While soil surface flux is widely studied, there are relatively few studies investigating the concentration and transport of greenhouse gases within the soil profile. The object of our study was to investigate these processes by using undisturbed soil monoliths. Since gas sampling is difficult especially from waterlogged or wet soils, we have developed a silicone-tube soil air sampler for soil monoliths. Six undisturbed soil monoliths have been prepared from the nearby long-term experimental field of Keszthely University. Silicone tubes have been inserted across the soil columns at three depths and the soil air composition was measured during a growth season of seeded maize. We found that the gases of interest (CO2 and N2O) could easily get through the wall of silicone tube while keeping out the water. The first experiment using silicone tubes showed reproducible results. The differences in vertical distribution of these gases were significant in case of CO2 while N2O distribution was quite even. CO2 and N2O concentrations of soil air have changed in time as maize root developed and the soil moisture changed by rainfall.

The convective flow in vertical cylindrical tubes is investigated and a new formula for its velocity is derived. The Ostroumov problem is briefly discussed, and the relevant fourth-order ordinary differential equation referring to this problem is solved directly in its complete form and within a frame of an allowed simplification, as well. The result obtained for the velocity function is in good qualitative agreement with earlier simulation calculations.

In this paper a survey is given concerning to the stochastic modelling approaches in transport processes with a special emphasis on application possibilities for simultaneous heat and mass transfer in drying. First, the mostly used classical modelling methods for drying are discussed which lead to a linear parabolic type of PDE systems supposing constant (state-independent) conductivity coefficients. Powerful discretisation methods are shown for their solution. Basic principles of variational calculus are discussed then with an attention on direct methods. As a simple application a first-order approximation example is formed, and the solution of the system equation is presented. It is also shown, that the thermodynamical state-dependence of the conductivity coefficients has a crucial influence on the flow pattern of the coupled heat and mass transfer, which is particularly obvious in the cases, when the so-called percolative phase transitions take place. It effects a discrete change of the conductivity coefficients and their probabilities as well. An illustration is shown for percolative phase transition. Describing statistical properties of percolative system the dynamic scaling theory was applied. Characterising the system decay a correlation length was introduced as a parameter. Finally, a simple case of two fields is described together with relevant transfer functions.

A twofold refinement of the basic mathematical model for describing a coupled heat and mass transfer taking place in porous media is presented. The common application of irreversible thermodynamics and fluctuation theory of phase transitions is proposed for calculating the moisture level and temperature. Instead of parabolic partial differential equations, hyperbolic type partial differential equations are used. The relaxation time constants, whose percolation state-dependence is also taken into account, are incorporated into this formalism. Some possible new research domains in mathematical and statistical physics are also indicated.

A new calculation is elaborated for the description of surface changes of temperature and matter due to coupled transport through a porous medium. It is based on a finite-size supposition (Neumann's type boundary condition) and on the solutions of parabolic type partial differential equations combined with Lambert's W-function. The boundary layer phenomena are also incorporated into the description of the general transport. The procedure leads to a direct computer simulation, providing concrete results on the real physical picture of the given problem in good agreement with some experiments analysed.

Abstract A new method is given for mathematical modeling of the coupled heat and mass transfer through porous media. The behavior of the moisture level function in the vicinity of the critical value of the conductivity probability is discussed, at general initial-, and boundary conditions. Instead of the usually applied two coupled partial differential equations of parabolic type, a coupled system of hyperbolic partial differential equations containing also explicitly the relaxation time constants is used. A general solution is presented for the moisture level function, when the relaxation time constant relevant for temperature changes tends to value zero. This description is combined with scaling relations following from the contemporary statistical physical theory of percolation phenomena.

Intensive application of N-fertilizer (inorganic and organic N-sources) may lead to water (nitrate leaching) and air (NOx, NH3 emission) pollution. Estimation and prediction of environmental hazard connected by N-fertilization requires modelling of N-cycling in agroecosystems. A three-level experimental system was built up for modelling the N-transformation processes running in different spatial and time scale in the soil/plant(biota)/atmosphere system. In 10 years harmonized series of micro-cosmos, meso-cosmos and field experiments using the stable isotopic 15N-tracer technique a solid data basis was collected for mathematical modelling. The three-compartmental mathematical model was based on the principles of the non-equilibrium thermodynamics. The experimental system made possible the quantitative estimation of plant—uptake and NOx-gas losses on a yearly scale. The mobilization/immobilization and nitrification/denitrification processes were described on a shorter-term scale (hours, days). The 20–80% of inorganic N-sources was taken up yearly by plants and NOx-gas losses were in the range of 10–25% of the source-N. The inorganic N-sources were totally depleted from the soil during the 3 years.

A new application of the percolation theory for describing the coupled heat and mass transport phenomena through porous media is given. The space and time dependence of the temperature and moisture level functions are calculated by taking into account the discrete, sudden changes of the diffusion coefficient in the vicinity of the critical points. A further possible application of the method leading to exact treatment of the thermodynamic state dependence of the conductivity and coupling coefficients is also indicated.

The application of (15)nitrogen (N)-tracer technique in soil N-transformation studies requires simultaneous determination of N-15/N-14 ratio and total N contents in large number of soil samples. Speciation of soil N compartments by means of extraction and separation procedures is also required. An optical emission spectrometric method was elaborated using atmospheric microwave induced plasma excitation which can be easily coupled with separation techniques and is suitable for analysis of solid/liquid and gaseous samples. The method was applied to kinetic modeling N-cycles in mesocosm experiments using N-15-labelled fertilizers as N sources.

The mobilization and immobilization processes of (NH4)-N-15 (NO3)-N-15 were studied in a laboratory soil core incubation model experiment by means of the N-15-tracer technique. Brown forest soil was filled into plastic tubes 40 cm high which were incubated for 30 days at 27 degrees C at different moisture levels. The soil columns were divided into 10 cm segments and sampled on the 10th, 20th and 30th days. Total carbon content, different N-forms of 1 M KCl extractable NH4+ and NO3-, mineralizable nitrogen and total nitrogen were determined in each segment of the control and treated soil samples. A low CM ratio (<20) was calculated from the data of total carbon and total nitrogen for all the soil samples.The recovery percentage of fertilizer N in different N forms was calculated from the N-15/N-14 isotopic ratio measurements. Extreme differences (6-50%) were found between the mineral and mineralizable forms of fertilizer N at different moisture levels. In addition, a relatively rapid development of the stationary state in mineral N forms was observed during the first ten days. The level of mineral and mineralizable forms of available nitrogen was found to be highly influenced by the moisture level in the soil.

A symmetry analysis based on line-group formalism is given for the YBa2Cu3O7-x high temperature superconductor with 7 - x = 6.55, which gives rise to a superlattice phase. The diffuse x-ray scattering intensity curves are calculated for each allowed supersymmetry. An analysis is given for comparison of the experimental and theoretical intensity profiles. (C) 1997 Academic Press Limited.

Abstract A combined procedure to detect of (15)N/(14)N isotope ratios by emission spectrometric analysis after starch gel-electrophoresis was developed. (15)N-labelled proteins of human serum were used to optimise this method. Electrophorised gel slices with protein fractions were directly digested for subsequent isotope analysis. This method is proposed for use in routine analysis for clinical application.